JPH08243747A - Wire filling mig welding method - Google Patents

Abstract

PURPOSE: To increase deposition quantity and to reduce welding heat input by stabilizing fusion of filler wire without effect of peculiarity of wire in the wire filling MIG welding method. CONSTITUTION: By oscillating a comsumable electrode 1 in the direction vertical to weld line in 5-50Hz and single vibration, the generating point of arc is widened and welding is executed with filling a filler wire 2 from the front of vibrating face. In the case the relative position between the consumable electrode 1 and filler wire 2 is varied due to peculiarity of wire, the filler wire is surely melted, as a result, increase of deposition quantity and reduction of welding heat input are made possible, further, welding quality such as increase of efficiency at welding position and reduction of weld deformation, etc., is improved. Also, different kind wires can be simultaneously fused, it is effective for composition adjustment of weld metal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire-added MIG welding method used for improving efficiency and quality in welding structural members such as pipes and thick plates and thin plates such as plated steel plates.

[0002]

2. Description of the Related Art In the conventional wire-added MIG welding method, a filler wire is fed directly under the arc of a consumable electrode and a part of the arc energy of the consumable electrode is allocated to melting the filler wire. The arc of MIG welding is smaller and more focused than the arc of TIG welding.
Further, since the target position of the wire is likely to change due to the influence of the line habit, stable melting of the filler wire could not be performed.
In the additive wire type magnetically controlled MIG welding method disclosed in JP-A-62-124077, the welding is stabilized while controlling the arc by using an alternating magnetic field, but it is easily affected by the conditions such as the welding posture, There are aspects that lack workability. On the other hand, in the consumable electrode type arc welding method disclosed in Japanese Unexamined Patent Publication No. 181821/1992, in order to eliminate the influence of the wire peculiarity, the filler wire is energized to form a hot wire and then fed to the molten pool to melt it. Although the amount of welding can be expected to increase because the energizing current becomes large, it cannot be said that it necessarily contributes to the decrease in welding heat input.

[0003]

DISCLOSURE OF THE INVENTION An object of the present invention is to increase the amount of welding and to improve the welding penetration by stabilizing the melting of the filler wire in the wire-added MIG welding without being affected by the wire habit. It is to provide a welding method for enabling the reduction of heat.

[0004]

In order to achieve the above-mentioned object, the wire-added MIG welding method of the present invention is to swing the feeding position of the consumable electrode at high speed to mechanically widen the position where the welding arc is generated. It is characterized in that the filler wire can be reliably melted without being affected by the habit of the wire.

That is, the gist of the present invention is as follows.
(1) In the welding method in which the filler wire is added to the molten pool immediately below the arc of the consumable electrode due to MIG welding, the consumable electrode feed position is set to 5 relative to the filler wire feed position.
Wire addition type MIG welding method characterized by oscillating at ~ 50Hz, and (2) to feed the consumable electrode to the filler wire so that the arc generated by the consumable electrode can efficiently target the filler wire. The wire-added MIG welding method described in (1) above is characterized by swinging so as to be a single vibration in a direction perpendicular to.

[0006]

As a result of various studies on the wire-added MIG welding, the present inventors have found that the method of melting the filler wire by applying the arc emitted by the consumable electrode directly to the filler wire is the most reliable method. Got However, the spread of the arc in MIG welding is small, and the target position of the wire easily fluctuates due to the influence of the line habit, so it is difficult to reliably melt the filler wire. Therefore, the feed position of the consumable electrode is set to 5
A method of mechanically expanding the arc generation point and melting the filler wire by oscillating at a high frequency of about 50 Hz was examined. The present invention will be described in detail below.

First, FIG. 1 shows a schematic view of the present welding method. Swing the consumable electrode 1 vertically at 5 to 50 Hz with respect to the welding line,
The filler wire 2 is fed from the front or the back of the rocking surface aiming at the rocking center. The consumable electrode can be oscillated by simple oscillation, rotational movement, or other oscillating method.In the case of rotational movement, the oscillating direction on the left and right of the welding line is opposite, but By vibrating the single vibration so that the left-right symmetry viewed from the welding line can be maintained and stable welding can be performed, the single vibration is preferable.
The swinging amplitude of the consumable electrode is not particularly specified, but it is preferably about 3 mm in consideration of the target deviation due to the habit of the wire.

Next, the swinging cycle of the consumable electrode and the feed amount of the filler wire will be described. FIG. 2 shows how much the filler wire is fed during one cycle of swinging of the consumable electrode. For example, when the feed rate of the filler wire is 2 m / min and the oscillation cycle of the consumable electrode is 20 Hz, the feed rate of the filler wire within one cycle is only 1.7 mm. By swinging the consumable electrode at high speed in this manner, it becomes possible to melt the filler wire little by little and almost continuously.

FIG. 3 is a diagram showing the weldability when welding is actually performed by changing the frequency of the consumable electrode and the feed amount of the filler wire. Welding current is 250A, swing amplitude 3mm
The welding position was downward bead on plate. The positional relationship between the consumable electrode and the filler wire is as shown in FIG. When the frequency was less than 5 Hz, the arc became unstable and the amount of spatter generated increased. It is considered that this is because the amount of the filler wire that the consumable electrode melts in one cycle increases, and the lower limit of the frequency in the welding method of the present invention is 5 Hz,
It is preferably 10 Hz. On the other hand, although the upper limit of the frequency is not particularly limited, when the frequency exceeds 50 Hz, there is a tendency that the molten pool overflows and the spatter increases, so the upper limit of the frequency is 5
Set to 0 Hz. On the other hand, the feed rate of the filler wire is 2 mm / cycle or less when the frequency of the consumable electrode is less than 30 Hz, and 3 m / min (about 40% of the wire feed rate of the consumable electrode) when the frequency of the consumable electrode is 30 Hz or more. Is preferred. Regarding the vibration amplitude, about 3 mm is suitable in consideration of the variation of the target position due to the wire habit. However, it is also possible to widen it to about 10 mm according to the groove width of the welded portion.

Next, the welding conditions will be described. It is better that the welding arc spreads from the viewpoint of ease of melting the filler wire. Therefore, high current MIG welding or welding using a flux-cored wire, in which the droplet transfer form is spray transfer, is suitable.

By swinging the consumable electrode under the above conditions, even if the relative position of the consumable electrode and the filler wire fluctuates to some extent due to the influence of the wire habit, it should be within the swing amplitude of the consumable electrode. For example, the filler wire can be reliably melted in one cycle.

[0012]

EXAMPLE A vertical upward welding of a thick plate will be described as an example. FIG. 4 shows a schematic view of the welding device. The mechanism of the oscillating portion is designed so that the rotational movement of the rotating shaft 4 is directly converted into the movability via the eccentric cam 3, and the consumable electrode 1 oscillates in a single vibration in the direction perpendicular to the welding line. The oscillating direction oscillates in the width direction of the groove 5, and the filler wire 2 is fed to the oscillating surface from the front in the welding direction while maintaining an angle of 60 ° with the consumable electrode. The filler wire is electrically insulated in order to prevent a part of welding current from flowing and causing interference of the arc.

Next, the welding method will be described with reference to FIG. Carbon dioxide welding was performed using SM400 steel as a base material, a flux-cored wire as a consumable electrode for a welding wire, and a solid wire as a filler wire. The shape of the groove is an I-shaped groove with a width of 7 mm and a height of 12.7 mm.

First, the consumable electrode is swung in the groove width direction, and then an electric current is passed to generate an arc. At the same time as the arc is generated, the filler wire is fed at a right angle to the vibration direction of the consumable electrode from the back in the direction of welding progress to start welding. The consumable electrode had an amplitude of 4 mm according to the groove width and was vibrated at 30 Hz.
The feed rate of the consumable electrode was 8 m / min, and the feed rate of the filler wire was 2.5 m / min. Welding was stable with little spatter, the molten metal did not burn through due to the cooling effect of the filler wire, and a clean bead appearance could be obtained. In addition, since there is little burn-through, the welding current can be increased by about 20% compared to the conventional MIG welding method that uses a filler wire, and the amount of deposition of the consumable electrode can be increased. Welding efficiency can be improved by 50% or more.

Next, FIG. 6 shows a schematic diagram of the macrostructure of the cross section of the welded portion in order to determine the welding result. It can be seen that there is no fusion defect, slag inclusion, or other welding defect on the side surface of the groove, and it is well melted. Further, from the schematic diagram of the macrostructure of the cross section of the welded portion shown in FIG. 7, welding can be performed with a smaller number of passes compared to the conventional MIG welding method without a filler wire, and the area of the heat affected zone is narrowed. It can also be seen that the heat has been reduced.

[0016]

As described above, according to the present invention, M
The filler wire can be reliably melted in IG welding. Therefore, it is possible to improve efficiency and reduce welding heat input by increasing the amount of welding. In addition, since the melt-through of the molten metal is reduced by the cooling effect of the filler wire, it is possible to stabilize the appearance shape in posture welding and prevent defects such as defective fusion. Furthermore, since different types of wires can be melted at the same time, it is effective for adjusting the composition of the weld metal.

[Brief description of drawings]

FIG. 1 Wire-added MI using an oscillating consumable electrode
It is a schematic diagram of G welding method.

FIG. 2 is a diagram showing a filler wire feed amount within one cycle of a consumable electrode.

FIG. 3 is a diagram showing the weldability when the frequency of the consumable electrode and the feed amount of the filler wire are changed.

FIG. 4 is a schematic diagram showing a mechanical configuration of a consumable electrode vibrating section.

FIG. 5 is a schematic view showing vertical welding according to the embodiment of the present invention.

FIG. 6 is a schematic view of a cross-sectional macrostructure of a welded portion by the wire addition type MIG welding method of the present invention.

FIG. 7 is a schematic view of a cross-sectional macrostructure of a welded portion by the conventional MIG welding method.

[Explanation of symbols]

 1 Consumable electrode 2 Filler wire 3 Eccentric cam 4 Rotating shaft 5 Groove

Claims (2)

[Claims] 1. In a welding method in which a filler wire is added to a molten pool immediately below an arc of a consumable electrode due to MIG welding, the feed position of the consumable electrode is swung at 5 to 50 Hz with respect to the feed position of the filler wire. A wire-added MIG welding method characterized in that 2. The wire-added MIG welding method according to claim 1, wherein the consumable electrode is oscillated in a direction perpendicular to the feeding direction of the filler wire so as to be a single vibration.